1. Field of the Invention
The invention relates in general to a scan assisting fixing device, and more particularly to a fixing device applicable to a scanning element with small field depth and a scanner using the same.
2. Description of the Related Art
The slides (positive films) have been widely used in many occasions such as business meetings, seminars or classes. Mostly, the positive films are realized by transparent thin films made from soft materials. Therefore, before the positive films are delivered from the factory, some positive film manufacturers normally use a positive film holder to enclose and protect the soft positive film as indicated in FIGS. 1A-1B. The positive film holder 100 includes a positive film 101 and a holding portion 102, wherein the positive film 101 is surrounded by the holding portion 102 and the to-be-scanned portion 1011 of the positive film 101 is exposed.
The positive film holders manufactured by different positive film manufacturers may have different specifications. In general, the thickness of the positive film holders currently available in the market may range between 1.0˜3.5 mm. The difference in the thickness of the positive film holder may cause problem when a positive films enclosed with a positive film holder is scanned.
Referring to FIG. 2, a diagram of an existing scanner scanning a positive film is shown. As indicated in the diagram, the scanner 20 includes a scanning element 200, which can be realized by a contact image sensor (CIS). The scanning element 200 has an imaging element (such as a lens) 201. The positive film holder 100 for scanning passes through a set of transmission rollers 202 to enter the scanner 200. Herein after, the distance from the imaging element 201 to the scan plane (the plane on which the positive film 101 is located) of the positive film holder 100 is referred as distance d. When scanning the positive film holders with different thicknesses, the variation range of the distance d may exceed the range of the field depth of the imaging element 201, so that the imaging element 201 cannot be focused clearly and the quality of the scanned image is unstable.
One of the commonly used methods is to remove the positive film from the positive film holder first, then the removed positive film is inserted into another auxiliary equipment and loaded into the scanner for scanning. However, the positive film may be damaged or spoiled during the process of removing the positive film from the positive film holder. Furthermore, such operation is inconvenient.